12 Questions
What is the primary difference between Spin Echo (SE) and Gradient Echo (GE) sequences?
SE uses RF pulses to rephase spins and eliminate inhomogeneity effects, while GE uses gradients to rephase spins and does not eliminate inhomogeneity effects.
Why is the Spin Echo sequence considered the 'gold standard' for most imaging applications?
It provides good image quality, is very versatile, allows true T2 weighting, and is sensitive to pathology.
How do Fast or Turbo Spin Echo sequences achieve reduced scan times compared to conventional Spin Echo sequences?
They perform more than one phase encoding step and fill more than one line of k-space per TR by using multiple 180° rephasing pulses to produce a train of echoes.
What are the typical parameter settings for T1-weighted imaging using a Spin Echo sequence?
Short TE (10-30 ms), short TR (300-700 ms), with a typical scan time of 4-6 minutes.
How does the TE (Echo Time) parameter setting affect the image contrast in Spin Echo sequences?
A short TE (20 ms) provides proton density weighting, while a long TE (80 ms+) provides T2 weighting.
What is the primary disadvantage of conventional Spin Echo sequences compared to other techniques?
Scan times are relatively long.
What is the primary advantage of using turbo spin echo imaging?
The primary advantage is that scan times are greatly reduced, allowing high-resolution matrices and multiple signal averages (NEX) to be used, thereby improving image quality.
What is a disadvantage of turbo spin echo imaging mentioned in the passage?
A disadvantage is that some flow and motion effects are increased, making it incompatible with some imaging options.
How does single shot fast spin echo (SS-FSE) imaging work?
In SS-FSE, all the lines of k-space are acquired in one repetition time (TR).
What is the mechanism behind inversion recovery pulse sequences?
Inversion recovery pulse sequences begin with a 180° inverting pulse, followed by a 90° excitation pulse applied at a time TI (time from inversion) later.
What is a typical use for inversion recovery pulse sequences?
Inversion recovery is usually used to suppress the signal from certain tissues in conjunction with long echo times (TEs) and T2 weighting.
What is the highest turbo factor currently used in single shot imaging according to the passage?
The highest turbo factor currently used in single shot imaging is 728.
Test your knowledge of MRI pulse sequences including Spin Echo (SE) and Gradient Echo (GE) sequences. Learn about the differences between conventional Spin Echo mechanism, Single Spin Echo, and Dual Echo & Multi Echo Sequences. Discover the uses of these sequences in MRI imaging.
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